Overdrive added behind Transmission?

[chaps70rt]

Just curious if anyone has added an overdrive to the driveshaft??   I met a Challenger owner who did this many years ago and said it was
fool proof.   Operates on a switch to engage the overdrive.     Have no knowledge on how easy this is or how effective it is.  Seems like a much less
invasive way to go and could be converted back for the purists out there.

Was hoping someone on this site has some experience and thoughts on whether it was worth doing??   Perhaps change the rear defog switch to
an overdrive switch??   At least that was my thoughts on the way to go.    With 3.55 gears and a 4-speed my engine is revving pretty high by the
time I get up to 60 mph.   Always looking for 5th ...... LOL.

[Cudajason]

i assume you are referring to a Gear Vendors overdrive.

Its ben done.

https://www.gearvendors.com/hrdodge3s.html

[Filthy Filbert]

Lots of people have done it.  It is nearly fool proof.   It also will empty your wallet.

I've heard of guys putting it on a 4-spd and using it in every gear.  1st, 1st OD, 2nd, 2nd OD, and so on...making it an "8 speed" manual

[dodj]

Lots of people have done it.  It is nearly fool proof.   It also will empty your wallet.

Last I checked it's cheaper than buying a 5 or 6 speed trans to replace the 833? I'm not trying to say it's cheap, but cheaper than buying a tkx or whatever.

[Filthy Filbert]

marginally cheaper, sure. 

We're talking what....$3k vs 4 or 5K?

[RUNCHARGER]

They're pretty much a tough, troublefree unit. My old boss sold lots of them. For me I think the best alternative is the Passon OD gearset in an A833 case and cam the engine to work with it. That's the cheapest option and it keeps the car stock with no modifications, no need to beat the tunnel, no need to cut the driveshaft. These engines can easily be built to work well with the wide ratios.

[Fastmark]

I've just finish my second Gear Vendor overdrive unit. My customers love them. I've installed the Passon OD  gears in two transmissions as well and attempted a third. We had problems installing the 3rd set and had to return them. The issues with the Passon gears is the spread is very undesirable. You loose to much rpm between shifts. They are noisy too. I no longer will install a set for a customer. The price went up to where the gear vendors is not much more. All you do is slot the holes a little and clearance  the tunnel very slightly. It's hardly noticeable. It's a no brainer to me. You'll love it.

[dodj]

marginally cheaper, sure. 

We're talking what....$3k vs 4 or 5K?

sounds about right